Vehicle height control system

Abstract

A vehicle height control system includes a plurality of vehicle height adjusters actuated by a pneumatic actuating system and controlled respectively by control signals from a control unit. The control unit calculates, for each of the vehicle height adjusters, a target difference between a target adjustment position and an actual position detected by a vehicle height sensor associated with the adjuster. The control unit compares the target differences for respective vehicle height adjusters, and the adjuster having the target difference which is the largest in magnitude is first actuated to perform its adjusting operation, thereby preventing unbalanced differences in the vehicle height.

We claim: 
     
       1. A vehicle height control system comprising: a plurality of vehicle height adjusters operated in response to respective control signals;   position signal generator means for generating actual position signals each representing a vehicle height of a wheel corresponding to one of said vehicle height adjusters;   setting means for changing target adjustment positions of respective vehicle height adjusters; and   control means for generating the control signal for each of said vehicle height adjusters in accordance with a target difference between the target adjustment position and the actual position signal to adjust the vehicle height to achieve the target adjustment position,   said control means comparing said target difference for each vehicle height adjuster with a first set value range (α 1 ) and generating an up-command to increase the vehicle height when said target difference exceeds an upper limit of said first set value range (α 1 ) and generating a down-command to decrease the vehicle height when said target difference is below said value range (α 1 ),   said control means comparing said target difference with a second set value range (α 2 ) smaller than said first set value range (α 1 ) and generating a cancel signal when said target difference enters into said second set value range (α 2 ), and   said control means selecting one of said target differences, for the respective adjusters, having the largest magnitude of absolute value of said target differences, and selecting one of said vehicle height adjusters corresponding to the selected target difference to thereby enable the selected vehicle height adjuster to perform its adjusting operation first, thereby taking priority over the other vehicle height adjusters.   
     
     
       2. A system according to claim 1, wherein said vehicle height adjusters are actuated by a plurality of actuating systems including two systems corresponding to right and left front wheels of a vehicle, and one system for adjusting right and left rear wheels commonly. 
     
     
       3. A system according to claim 1 wherein said control means maintains a previous command when any of said target differences enters into said first set value range (α 1 ). 
     
     
       4. A system according to claim 1, wherein said control means (a) fetches said actual position signals from said position signal generator means and said target adjustment position signals from said setting means a number of times during a predetermined time (T 0 ),   (b) obtains after the lapse of said predetermined time (T 0 ), an average target difference for each of said vehicle height adjusters based on said signals fetched for the number of times,   (c) generates the control signal for each of said vehicle height adjusters in accordance with said average target difference, and repeats the operations (a), (b), and (c).   
     
     
       5. A vehicle height control system comprising: a plurality of vehicle height adjusters operated in response to respective control signals;   position signal generator means for generating actual position signals each representing a vehicle height of a wheel corresponding to one of said vehicle adjusters;   setting means for changing target adjustment positions of said vehicle height adjusters respectively; and   control means (a) for fetching said actual position signals a number of times during a predetermined time (T 0 ),   (b) for obtaining a target difference for each of said vehicle height adjusters, said target difference corresponding to an average difference between the actual position signal and the target adjustment position obtained based on said actual position signals fetched the number of times and based on said target adjustment positions during said predetermined time (T 0 ),   (c) for generating the control signal for each of said vehicle height adjusters in accordance with said target difference after the lapse of the predetermined time (T 0 ) thereby enabling said each of said vehicle height adjusters to perform adjusting operation of the vehicle height to reach said target adjustment position;      wherein said control means compares said target difference with a first set value range (α 1 ) and generates an up-command to increase the vehicle height when said target difference exceeds an upper limit of said first set value range (α 1 ) and generates a down-command to decrease the vehicle height when said target difference is below said value range (α 1 ),   said control means compares said target difference with a second set value range (α 2 ) smaller than said first set value range (α 1 ) and generates a cancel signal when said target difference enters into said second set value range (α 2 ), and   said control means selects one of said target differences, for the respective adjusters, having the largest magnitude of absolute value of said target differences, and selects one of said vehicle height adjusters corresponding to the selected target difference thereby enabling the selected vehicle height adjuster to perform its adjusting operation first, thereby taking priority over the other vehicle height adjusters.